Lochinvar combi and condensing commercial units use either a hot surface igniter (silicon nitride rod) or a spark electrode depending on the platform. Both wear out over years of cycling.
Igniter types by platform
- NOBLE NKC: hot surface igniter
- KNIGHT WHN: hot surface igniter on most generations
- ARMOR commercial: hot surface igniter
- EnergyRite atmospheric: spark electrode + pilot
Symptoms of failure
- E04 ignition failure code
- Repeated ignition trials before flame establishes
- Visual: cracked, eroded, or broken silicon nitride rod
- Spark electrode: visible carbon buildup or eroded tip
Replacement procedure
- Power off at breaker
- Close gas supply at the boiler shutoff
- Remove burner cover and front panel
- Disconnect igniter wire (high-voltage on spark; 120V on hot surface)
- Unscrew or unclip igniter from mounting bracket
- Inspect old igniter for cracking and electrode gap
- Install new igniter with new gasket (where applicable)
- Reconnect wire; verify gap on spark electrode (0.10-0.12")
- Restore gas, power; verify successful ignition
Critical handling
- Silicon nitride is brittle — never touch the surface with bare hands (oils contaminate). Handle by base only
- Spark electrodes — gap is critical; out of spec = no spark or weak spark
- Replace gasket every time — burner cover seal is essential
Cost
- Hot surface igniter (OEM): $40-80
- Spark electrode: $30-60
- Contractor labor: $150-250 (typically bundled with annual service)
Lifespan
Hot surface igniters typically last 5-8 years on residential combis. Heavy-cycling installations (e.g., combi with frequent short DHW calls) wear igniters faster. Annual service should include visual inspection.
Bottom line
Igniter is a routine wear item. Replace at first signs of degradation; bundle with annual service. $40-80 part vs $1,500-2,500 heat exchanger if E04 lockouts go ignored and heat exchanger overheats from repeated ignition attempts.